Machinery

Steel Tubes for Machinery Components

Sleeves, bushings, spacers, rollers and barrels are machined parts, not stock material. The tube specification is only complete when the drawing’s controlling dimension, the machining allowance and the final surface requirement are stated together.

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Machinery duties

Six component types, six different controlling requirements

An application label does not approve a material. What varies between these parts is which measurement decides whether the machined component is acceptable.

Sleeves and bushings

The bore carries the fit. Review whether the drawn bore is used as-supplied or whether a finishing step establishes the final geometry and surface.

Spacers and distance pieces

Length and squareness usually control the assembly. Confirm how cut length and end condition are stated and measured.

Rollers and idler bodies

Rotating duty adds balance and runout to the dimensional question. Name which dimension governs acceptance before the order is released.

Actuator and cylinder barrels

A pressure-containing duty adds bore geometry, final surface and pressure-design review to the tube specification. This is a different enquiry from a structural sleeve.

Guide and support columns

Straightness and outside-diameter control matter more than the bore. State which one governs and treat the other as reference.

Machine-frame tube elements

Where the tube is welded into a frame rather than machined, review whether a hollow section or a structural tube is the correct family before specifying a drawn mechanical tube.

Selection logic

Match the tube requirement to how the bore is actually used

This is the decision that most often changes the order. Work down the list until one state matches your drawing.

1

The bore is machined after delivery

State the machining allowance explicitly. A drawn bore used as a machining starting point is a different requirement from a bore used as-supplied.

2

The bore is used as-supplied

Name the measured surface parameter and the acceptance method. “Smooth bore” is not an acceptance criterion, and the word DOM does not supply one.

3

The part rotates

Add runout or balance requirements to the enquiry. These are not implied by dimensional control of the tube.

4

The part is welded into an assembly

Confirm the weldability requirement for the ordered grade and condition, and state it as a separate field rather than assuming the grade covers it.

5

The drawing requires a seamless product

Say so explicitly. Drawing a welded tube does not remove its manufacturing origin, and the DOM route will not satisfy a seamless-only requirement.

Machining allowance

Put the allowance and the governing dimension on the enquiry

A tube that is dimensionally correct but leaves insufficient stock is still unusable. State the allowance as a number and name the dimension it applies to.

  1. 1State the final machined bore and outside dimensions from the drawing revision.
  2. 2State the allowance left on each surface for machining, with its unit.
  3. 3Name which dimension governs acceptance of the delivered tube — OD, ID or wall.
  4. 4State the measurement method and the inspection scope agreed for that dimension.
  5. 5State the thermal condition, so the machining plan is set against the delivered condition rather than an assumed one.
  6. 6State how heat identity is carried through cutting, so the certificate still describes the pieces that arrive.

What the mill needs to confirm

  • The simultaneous OD, ID and wall limits can be met together
  • The ordered thermal condition is available at the offered size
  • The dimensional schedule matches the stated controlling pair
  • Any finishing step is inside the quoted scope, or explicitly excluded
  • Documentation matches the revision the drawing release refers to

Feasibility, availability and cost are confirmed in writing on quotation.

No tolerance value is published on this page. Acceptance limits come from the governing standard edition or from your drawing.

Related pages

Continue from the application to the tube specification

The component duty comes first. The route, the grade and the dimensional basis follow it.